BIO 112 Flashcards
What are the 5 steps of the scientific method?
- Make observation
- Develop hypothesis
- Run experiment
- Analyze results
- Draw conclusions
It’s winter and I’m growing spinach indoors. I want the plants to produce as much as possible. I normally water them twice a week but I’m thinking that if I water them 4 times a week, they will become bigger plants. So I’ll try both watering schedules and see what happens. List the variables:
Independent: amount of water
Dependent: amount of spinach produced
Standardized: growing conditions (fertilizer, sunlight, etc.)
Define element.
Pure substance
Define atom.
The smallest unit of a pure substance
Define ion.
Atom with a positive or negative charge
What is a cation and how is it formed?
Atom with a positive charge - it has lost an electron
What is an anion and how is it formed?
Atom with a negative charge - it has gained an electron
What happens regarding electrons in an ionic bond?
Electron transferred from one atom to another
What happens regarding electrons in a nonpolar covalent bond?
Electrons shared equally
What happens regarding electrons in a polar covalent bond?
Electrons shared unequally
Define electronegativity and explain its role in determining what chemical bonds occur.
The ability for an atom to attract electrons. If the electronegativity difference between 2 atoms is
small, it forms a nonpolar bond. If it is large, it forms an ionic bond. Moderate differences form a
polar bond.
Describe why one end of a water molecule carries a slightly negative charge and the other carries a slightly positive charge.
Oxygen pulls harder on electrons than hydrogen
Which end carries the negative charge and which end carries the positive charge?
Oxygen - negative
Hydrogren - positive
Define hydrogen bonds.
Occurs when the partial negatively-charged end of one polar molecule lines up with the partial positively-charged end of a different polar molecule
Water is cohesive. Define cohesion.
Water molecule linked to other water molecules with hydrogen bonds
Water is adhesive. Define adhesion.
Water molecule linked to other polar molecules with hydrogen bonds
Why is water an excellent solvent?
Water is polar, so the positive side of a polar or ionic compound is attracted to the oxygen side of water, and the negative side of the compound is attracted to the positive side of water. This is why polar or ionic substances dissolve in water.
Define hydrophilic and explain the chemistry involved.
Dissolves in water. Charged water molecules attracts charged polar or ionic molecules
Define hydrophobic and explain the chemistry involved.
Doesn’t dissolve in water. Charged water molecules repel uncharged nonpolar molecules
Define carbon skeleton.
Forms the framework of the molecule
Define functional group.
Gives the molecule a specific function
Define monomer.
A molecular building block. Monomers join to make polymers.
Define polymer.
A molecule made up of two or more monomers
What is dehydration synthesis?
Process that produces water during the chemical bonding of a monomer and a polymer
What is hydrolysis?
Water is added to a polymer in order to split off a monomer
List two different energy storage carbohydrates and write whether they are found in plants or animals.
Starch is found in plants
Glycogen is found in animals
List two different carbohydrates that provide structural support and write whether they are found in plants or animals.
Cellulose is found in plants
Chitin is found in animal exoskeletons and fungi
Why are polysaccharides usually hydrophilic?
Because they are polar
Fats are composed of…
glycerol and 3 fatty acids
What is the main function of a fat?
Fats store energy
Are fats hydrophobic or hydrophilic? Why?
Hydrophobic
They have non polar bonds
Phospholipids are composed of a head and tail that contain…
Head: glycerol and a phosphate group
Tail: 2 fatty acids
Is a phospholipid head hydrophilic or hydrophobic? Why?
Hydrophilic
The phosphate group carries a negative charge
Is a phospholipid tail hydrophilic or hydrophobic? Why?
Hydrophobic
It has non polar bonds
What is the function of a steroid?
Steroids are chemical messengers
Proteins are composed of…
amino acid monomers
What are the 6 functions of proteins? Describe them.
- Signaling - sends and receives chemical messengers
- Transport - proteins move oxygen and carbon dioxide through the body
- Structure - ligaments join bone to bone; tendons join muscle to bone
- Protection - skin protects the body from infection and from drying out
- Movement - muscles are made out of protein
- Defense - proteins include antibodies of the immune system
How are the phospholipid molecules oriented within a phospholipid bilayer?
Hydrophobic tails point toward center of the membrane, hydrophilic heads point toward cytoplasm and cell exterior
Describe how phospholipid chemistry controls what moves through the membrane.
Since the center of the membrane is hydrophobic, only hydrophobic molecules can pass freely through the membrane
List molecules that can easily pass through the membrane.
Any molecule whose atoms are linked with non polar bonds
List molecules that cannot pass through the membrane without help.
Polar or ionic molecules
What is the help that allows these molecules to pass through a membrane?
They travel through protein channels, not directly through the membrane
What role does a concentration gradient play regarding the movement of molecules across a cell membrane?
It provides the energy necessary to make molecules move from high to low concentration
Explain the difference between active and passive transport in terms of energy and concentration gradients.
Passive transport: concentration gradient provides energy to move molecules from high to low concentration
Active transport: cell provides energy to move molecules against the concentration gradient
Simple diffusion across a cell membrane:
What type of molecules are transported?
Molecules with non polar bonds
Simple diffusion across a cell membrane:
Can molecules move directly through a cell membrane? Why or why not?
Yes, they are hydrophobic, same as the cell membrane
Simple diffusion across a cell membrane:
Do molecules move up or down the concentration gradient?
Down
Simple diffusion across a cell membrane:
Is this a form of passive or active transport?
Passive
Osmosis across a cell membrane:
What type of molecules are transported?
Water
Osmosis across a cell membrane:
Can molecules move directly through a cell membrane? Why or why not?
No, the hydrophobic cell membrane repels the polar, hydrophilic water molecules
Osmosis across a cell membrane:
Do molecules move up or down the concentration gradient?
Down
Osmosis across a cell membrane:
Is this a form of passive or active transport?
Passive
Facilitated diffusion across a cell membrane:
What type of molecules are transported?
Molecules with polar or ionic bonds
Facilitated diffusion across a cell membrane:
Can molecules move directly through a cell membrane? Why or why not?
No, the hydrophobic cell membrane repels the polar, hydrophilic molecules. They can only move through protein channels.
Facilitated diffusion across a cell membrane:
Do molecules move up or down the concentration gradient?
Down
Facilitated diffusion across a cell membrane:
Is this a form of passive or active transport?
Passive
Describe the difference between a hypotonic, hypertonic, and isotonic environment.
Hypotonic: : Environment surrounding the cell is less concentrated than the cell. Water moves into the cell.
Isotonic: Concentration is the same inside and outside of the cell. No net water movement.
Hypertonic: Environment surrounding the cell is more concentrated than the cell. Water moves out of the cell.
Explain what happens to a blood cell and to a plant cell when each is placed in a hypotonic solution. Also explain why this happens to each type of cell.
In both cases, water moves into the cells. Plants have cell walls, so they can hold a lot of water pressure without bursting. But animal cells only have a cell membrane, and an influx of water can cause the cell to burst and die.
List the two parts of the cell theory and explain what basic question the cell theory can’t answer.
- Cells are the basic units of life and all cells come from other cells
- It can’t explain the origin of life
List three functions essential to all life that prokaryotes conduct.
Form the base of every food web, make nitrogen available to all organisms, produce global recycling of nutrients and carbon through decomposition
List prokaryotic and eukaryotic organisms.
Prokaryotic: bacteria, archaea
Eukaryotic: animals, plants, fungi, protists
What 4 things are found in both prokaryotic and eukaryotic cells?
- Nucleic acids (DNA & RNA)
- Cell membrane
- Ribosomes
- Cytoplasm
List the differences between plant and animal cells.
Plants have cell walls, large central vacuoles, and chloroplasts
Describe how endosymbiosis provides a possible explanation for the evolution of eukaryotic cells.
Eukaryotic cells originated when archaea cells engulfed bacteria and those bacteria became part of the archaeal cell. The first eukaryotes were protists with mitochondria - some of these cells engulfed photosynthetic bacteria which became chloroplasts in algae and plants
Organelles:
What is the function of a nucleus?
Control center of the cell
Organelles:
What is the function of a vacuole?
Location of storage materials
Organelles:
What is the function of a ribosome?
Location of protein synthesis
Organelles:
What is the function of a chloroplast?
Location where photosynthesis occurs
Organelles:
What is the function of a mitochondria?
Location of energy production
Organelles:
What is the function of a lysosome?
Recycling center of the cell
Organelles:
What is the function of the Golgi appratus?
Modifies membrane-embedded proteins
